If we're talking about YouTube, they can remove the video or remove the music from the video if they detect someone else's copyright being used.
Fair use in entertainment allows limited, unlicensed use of copyrighted material for purposes like commentary, criticism, news reporting, or parody.
I think Jagex would be happy if you used RuneScape content, including music, to make entertainment videos because it just promotes the game.
As for being banned, the RuneScape terms of service say you can make a new account.
The most recommended freeware music I know is https://www.youtube.com/@NoCopyrightSounds
A lot of my friends are also making AI music with https://suno.com, but typically you need to pay for the copyright rights to use AI music.